Evaluation of Inspiratory Muscular Force (Plmax) during Weaning from Mechanical Ventilation in Neurological Patients in the Intensive Care Unit

Abstract

Mechanical ventilation, often needed in critically ill patients, may be associated to loss of respiratory muscular force due to several mechanisms. The objective was to assess the progression of respiratory muscular force during weaning from mechanical ventilation by using serial measurement of maximum inspiratory pressure until complete discontinuation in neurological patients. The PImax was progressively assessed by using manovacuometer and unidirectional valve once a day during the whole period of mechanical ventilation weaning. Thirty-one neurological patients (after stroke or craniocerebral trauma) undergoing weaning from mechanical ventilation were included for study, and the values obtained were compared to those established by Black and Hyatt. The initial mean PImax (first day of weaning) was - 40.0±20.0 cmH2O (39% of the expected value) (p < 0.05), reaching 50% at day 5 and 60% at day 10. It was observed an increase of 21% (p < 0.05) between the first and tenth days. On the 13th day, mechanical ventilation had been completely discontinued in all patients. Therefore a progressive evaluation of the inspiratory muscular force in patients undergoing prolonged mechanical ventilation shows that the complete discontinuation is possible in neurological patients with 72% of the established values.